Ruby-throated Hummingbird
| Scientific Name | Archilochus colubris |
| Survival Strategy | Long-distance migrants |
| Arrival in Upper Midwest | Early to mid-May |
| Departure | August through October |
| Destination | Gulf Coast, Florida, Mexico, and Central America |
| Conservation status | Least Concern |
Winter
Ruby-throated hummingbirds spend the winter in the tropical warmth of the gulf coast, Florida, Mexico, and Central America. In January through February, they feed on flower nectar and insects while completing their winter molt. By the end of February, a migratory restlessness called “Zugunruhe” sets in.
Spring
The spring migration progresses slowly in March and April as hummingbirds follow the blooming of flowers northward. Courtship, mating, and nest building take place in May.
Summer
Females incubate and feed hatchlings through June. Young hummingbirds fledge in July, and a second brood is typical. The remainder of the summer, hummingbirds build a fat reserve that will fuel their fall migration.
Fall
The trip to the wintering grounds begins in earnest in August and continues through October. By November, successful migrants are in the tropics, spending their days visiting flowers, eating small insects, and beginning their winter molt.
Behavior
Mating
A male ruby-throated hummingbird aggressively defends his territory from other male hummers. When a female enters the territory, he will perform an aerobatic pendulum display flight to impress her. If it works, they will mate, and the female will leave to start her brood. All parenting becomes the responsibility of the female. The male will repeat his performance for the next female to enter his territory. By early August, male hummingbirds begin migrating south, weeks ahead of the females and hatch-year birds.
Hyperphagia
In the weeks before migration begins, hummingbirds go on a feeding frenzy called hyperphagia. The menu includes nectar needed to fuel the feeding frenzy and nutrient-rich insects to “bulk up” for migration. The protein from the insects will build muscle, while the insects’ fat becomes stored energy for the hummingbirds’ migration.
Physiology
Fat as fuel
There is twice as much energy available to migrating hummingbirds in fat than carbohydrates (nectar) or protein (insects). As a bonus, metabolizing fat releases twice as much water as carbohydrates or protein, preventing dehydration.
Piloerection
Hummingbirds do not have down feathers to help insulate them from the cold. By fluffing their contour feathers (piloerection), the hummingbirds trap warm air and reduce the number of calories they need to survive the cold.
Daily torpor
During cold nights, hummingbirds may enter a sleep-like state called torpor to conserve energy. These tiny birds will lower their body temperature by almost 50 degrees and slow their metabolism in torpor. Adaptations in their feet ensure no danger of a “sleeping” bird falling out of a tree. When a hummingbird (or other perching birds) sits down on a branch, flexor tendons in its foot tighten, forcing the toes to lock around the perch. As long as the bird is sitting, it can’t fall off a branch even if it is unconscious.
Shivering
Hummingbirds may begin shivering to create extra warmth in cold weather. Unlike humans, birds do not shake when they shiver; instead, they rapidly contract opposing muscle groups.
Diet
Hummingbirds feed on sugary plant nectar, spiders, and small insects. They will also drink sap from the wells that yellow-bellied sapsuckers drill into the trunks of trees.
Each day they will guzzle more than their body weight in nectar, manipulating their two-part tongues to trap the sweet liquid (hummingbird tongues are not straws). They may also eat more than 1000 insects a day.
Lifespan and Mortality
Ruby-throated hummingbirds typically live from 6 to 12 years. The annual survival rate is 30% to 45%
Causes of mortality
Animals that prey on ruby-throated hummingbirds include blue jays, domestic cats, bats, and toucans. Other causes of hummingbird mortality are window collisions, dirty hummingbird feeders, and cold weather.
Climate Vulnerability
Climate modeling indicates that the summer and winter range of the ruby-throated hummingbird will be stable in a warmer climate.
Ruby-throated Hummingbirds are arriving earlier to their breeding grounds. Biologists are monitoring this trend for possible impact on the population.
Never stop learning
First Nations: The Ojibwe word for hummingbird is “nenookaasi”.
Plumology: The patch of metallic-red throat feathers of a male ruby-throated hummingbird is called a gorget. (Plumology is the study of feathers)
Snapple® Cap Worthy: Hummingbirds can fly backward or upside down, but they cannot walk.
References
| Weidensaul, S., T. R. Robinson, R. R. Sargent, M. B. Sargent, and T. J. Zenzal (2020). Ruby-throated Hummingbird (Archilochus colubris), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.rthhum.01 |
| Journey North-Hummingbirds https://journeynorth.org/hummingbirds |
| Jason R. Courter, Ron J. Johnson, William C. Bridges, Kenneth G. Hubbard “Assessing Migration of Ruby-Throated Hummingbirds (Archilochus colubris) at Broad Spatial and Temporal Scales,” The Auk, 130(1), 107-117, (January 1, 2013) https://doi.org/10.1525/auk.2012.12058 |
| “The hummingbird tongue is a fluid trap, not a capillary tube.” Alejandro Rico-Guevara and Margaret A. Rubega. Proceedings of the National Academy of Sciences. Published online May 2, 2011, DOI: 10.1073/pnas.1016944108. https://doi.org/10.1073/pnas.1016944108 |
| Ojibwe People’s Dictionary: Hummingbird https://ojibwe.lib.umn.edu/main-entry/nenookaasi-na |